The present invention relates to field of automated manufacture and assembly. More specifically, the present invention relates to the robotic welding within small metal enclosures.
Distribution transformers commonly employ mounting brackets to keep the transformer""s core stationary within the transformer""s enclosure. Usually, two or more brackets are welded to the inside of the transformer""s enclosure, adjacent to each side of the core. The core then may be bolted to the mounting brackets by a brace or similar connection device. An anchored transformer core prevents inductive shorting between the transformer and its enclosure during normal operation by maintaining the minimum spacing requirements established during manufacture. This stability is especially important while the transformer is transported from the manufacturing line to the field.
To date, mounting brackets inside transformer enclosures have been welded by human welders because grounding concerns and space constraints have prevented using robotics.
Specifically, the limited area inside the transformer enclosure (typically, the enclosure takes the form of a rectangular box with dimensions of about 24 inches in height, 32 inches in depth, and 12 inches deep) precludes the enclosure from accepting the two robotic arms needed to weld the bracket to the inside of the enclosure: one arm to hold and locate the bracket and the other arm to weld the bracket. In addition, the confined space prevents the robot from being sufficiently accurate in locating the bracket within the enclosure. Another problem associated with using robotics to weld brackets inside a transformer enclosure involves providing the necessary ground path for the high welding currents. Currently, human intervention is necessary to clamp a ground onto the device being welded. However, because of the potential danger created by human and robotic interaction, it is necessary to automate the entire bracket mounting process, including affixing the ground connection. Therefore, an automated ground connection is required. Significantly, the automated ground connection can not be provided by a robot because of the dangerous welding currents that may travel through the robot""s electronically sensitive arm.
Aside from safety concerns, another reason it would be beneficial to automate the process of constructing a transformer enclosure is that such automation would make the process more efficient and thus less expensive for the customer and thus more profitable for the manufacturer. Automation would also permit the end product to be built to the customer""s specifications in a more efficient and cost effective way. For example, the customer could specify the desired product using the Internet as a means for filling out specialized forms in which the dimensions and other aspects of the product are defined. Such specifications could then be used as inputs to an automated process for building the end product to the customer""s specifications.
Because of the distinct benefit offered by automation, it would be advantageous to provide a method for allowing robots to weld mounting brackets inside transformer enclosures and for providing an automated, non-robotic ground connection for the method.
The present invention provides a system and method for attaching a device to an inside wall of an enclosure. The device is removably attached to a positioner. Where the device includes a metal substance, it may be attached to the positioner by a magnet affixed to the positioner, for example. A first motor-operated moving device moves the enclosure such that the device abuts an inside wall of the enclosure. A second motor-operated moving device, for example a robot, then attaches the device to the inside wall of the enclosure. Where the enclosure and the device are composed of metal, the two may be welded together. In this instance, the first motor-operated moving device may be a non-robotic, motor-operated moving device that provides a ground path for the weld.